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Search in rotated sorted array II
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‎81.search_in_rotated_sorted_array_ii/search.go‎

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// 81. Search in rotated sorted array II
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// Topics: 'Array', 'Binary Search'
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// There is an integer array nums sorted in non-decreasing order (not necessarily with distinct values).
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// Before being passed to your function, nums is rotated at an unknown pivot index k (0 <= k < nums.length) such that the resulting array is [nums[k], nums[k+1], ..., nums[n-1], nums[0], nums[1], ..., nums[k-1]] (0-indexed). For example, [0,1,2,4,4,4,5,6,6,7] might be rotated at pivot index 5 and become [4,5,6,6,7,0,1,2,4,4].
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// Given the array nums after the rotation and an integer target, return true if target is in nums, or false if it is not in nums.
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// You must decrease the overall operation steps as much as possible.
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// Example 1:
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// Input: nums = [2,5,6,0,0,1,2], target = 0
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// Output: true
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// Example 2:
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// Input: nums = [2,5,6,0,0,1,2], target = 3
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// Output: false
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// Constraints:
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// 1 <= nums.length <= 5000
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// -104 <= nums[i] <= 104
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// nums is guaranteed to be rotated at some pivot.
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// -104 <= target <= 104
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package searchinrotatedsortedarrayii
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func search(nums []int, target int) bool {
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L, R := 0, len(nums)-1
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for L <= R {
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L, R = skipDuplicates(nums, L, R)
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m := (L + R) / 2
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if target == nums[m] {
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return true
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}
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if nums[L] <= nums[m] {
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if target < nums[m] && target >= nums[L] {
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//sorted
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R = m - 1
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} else {
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L = m + 1
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}
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} else {
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if target > nums[m] && target <= nums[R] {
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//sorted
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L = m + 1
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} else {
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R = m - 1
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}
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}
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}
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return false
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}
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func skipDuplicates(nums []int, L, R int) (int, int) {
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for L < R {
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if nums[L] == nums[L+1] {
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L++
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continue
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}
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if nums[R] == nums[R-1] {
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R--
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continue
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}
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if nums[R] == nums[L] {
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R--
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continue
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}
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break
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}
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return L, R
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}

‎81.search_in_rotated_sorted_array_ii/search_test.go‎

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package searchinrotatedsortedarrayii
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import "testing"
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func TestSearch(t *testing.T) {
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tests := []struct {
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name string
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nums []int
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target int
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want bool
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}{
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// Basic examples from problem
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{
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name: "Example 1: target exists",
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nums: []int{2, 5, 6, 0, 0, 1, 2},
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target: 0,
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want: true,
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},
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{
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name: "Example 2: target doesn't exist",
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nums: []int{2, 5, 6, 0, 0, 1, 2},
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target: 3,
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want: false,
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},
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// Single element
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{
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name: "Single element - found",
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nums: []int{1},
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target: 1,
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want: true,
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},
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{
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name: "Single element - not found",
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nums: []int{1},
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target: 0,
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want: false,
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},
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// Two elements
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{
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name: "Two elements - first",
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nums: []int{1, 3},
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target: 1,
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want: true,
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},
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{
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name: "Two elements - second",
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nums: []int{1, 3},
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target: 3,
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want: true,
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},
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{
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name: "Two elements - not found",
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nums: []int{1, 3},
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target: 2,
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want: false,
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},
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// All duplicates
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{
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name: "All same elements - target exists",
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nums: []int{1, 1, 1, 1, 1},
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target: 1,
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want: true,
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},
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{
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name: "All same elements - target doesn't exist",
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nums: []int{1, 1, 1, 1, 1},
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target: 2,
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want: false,
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},
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// Duplicates with rotation
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{
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name: "Duplicates at boundaries",
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nums: []int{1, 1, 1, 2, 1, 1, 1},
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target: 2,
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want: true,
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},
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{
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name: "Many duplicates - target at beginning",
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nums: []int{2, 2, 2, 3, 4, 2},
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target: 3,
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want: true,
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},
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{
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name: "Many duplicates - target at end",
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nums: []int{3, 1, 2, 2, 2, 2},
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target: 1,
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want: true,
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},
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// No rotation (already sorted)
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{
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name: "No rotation - sorted array",
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nums: []int{1, 2, 3, 4, 5},
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target: 3,
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want: true,
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},
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{
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name: "No rotation - target not found",
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nums: []int{1, 2, 3, 4, 5},
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target: 6,
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want: false,
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},
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// Heavy rotation
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{
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name: "Rotated at last position",
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nums: []int{5, 1, 2, 3, 4},
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target: 1,
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want: true,
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},
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{
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name: "Rotated in middle",
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nums: []int{4, 5, 6, 7, 0, 1, 2},
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target: 0,
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want: true,
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},
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// Edge cases with duplicates
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{
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name: "Target equals boundary duplicates",
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nums: []int{1, 3, 1, 1, 1},
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target: 1,
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want: true,
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},
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{
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name: "Two distinct values with duplicates",
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nums: []int{1, 1, 3, 1},
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target: 3,
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want: true,
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},
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// Negative numbers
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{
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name: "Negative numbers - found",
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nums: []int{-5, -3, -1, 0, 2, 4},
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target: -3,
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want: true,
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},
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{
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name: "Negative numbers - not found",
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nums: []int{-5, -3, -1, 0, 2, 4},
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target: -2,
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want: false,
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},
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{
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name: "Mixed negative and positive",
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nums: []int{3, 4, 5, -5, -3, -1, 0, 1},
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target: -3,
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want: true,
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},
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// Target at different positions
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{
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name: "Target at beginning",
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nums: []int{3, 4, 5, 1, 2},
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target: 3,
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want: true,
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},
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{
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name: "Target at end",
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nums: []int{3, 4, 5, 1, 2},
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target: 2,
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want: true,
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},
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{
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name: "Target in middle",
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nums: []int{4, 5, 6, 7, 0, 1, 2},
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target: 6,
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want: true,
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},
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// Complex duplicate patterns
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{
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name: "Duplicates everywhere",
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nums: []int{2, 2, 2, 3, 2, 2, 2},
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target: 3,
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want: true,
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},
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{
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name: "Duplicates everywhere - not found",
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nums: []int{2, 2, 2, 3, 2, 2, 2},
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target: 4,
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want: false,
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},
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// Boundary values
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{
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name: "Max constraint values",
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nums: []int{10000, -10000, 0},
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target: -10000,
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want: true,
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},
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{
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name: "Zero in array",
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nums: []int{0, 0, 1, 2, 0},
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target: 0,
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want: true,
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},
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}
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for _, tt := range tests {
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t.Run(tt.name, func(t *testing.T) {
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got := search(tt.nums, tt.target)
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if got != tt.want {
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t.Errorf("search(%v, %d) = %v, want %v", tt.nums, tt.target, got, tt.want)
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}
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})
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}
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}
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func TestSkipDuplicates(t *testing.T) {
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tests := []struct {
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name string
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nums []int
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L int
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R int
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wantL int
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wantR int
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}{
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{
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name: "No duplicates",
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nums: []int{1, 2, 3, 4, 5},
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L: 0,
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R: 4,
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wantL: 0,
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wantR: 4,
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},
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{
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name: "Duplicates at left",
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nums: []int{1, 1, 1, 2, 3},
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L: 0,
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R: 4,
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wantL: 2,
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wantR: 4,
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},
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{
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name: "Duplicates at right",
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nums: []int{1, 2, 3, 3, 3},
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L: 0,
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R: 4,
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wantL: 0,
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wantR: 2,
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},
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{
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name: "Duplicates at both ends",
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nums: []int{1, 1, 2, 1, 1},
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L: 0,
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R: 4,
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wantL: 1,
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wantR: 2,
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},
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{
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name: "All same elements",
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nums: []int{1, 1, 1, 1, 1},
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L: 0,
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R: 4,
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wantL: 4,
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wantR: 4,
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},
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{
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name: "Two elements - same",
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nums: []int{1, 1},
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L: 0,
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R: 1,
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wantL: 1,
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wantR: 1,
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},
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{
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name: "Two elements - different",
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nums: []int{1, 2},
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L: 0,
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R: 1,
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wantL: 0,
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wantR: 1,
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},
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{
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name: "Complex pattern",
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nums: []int{1, 1, 1, 2, 1, 1, 1},
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L: 0,
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R: 6,
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wantL: 2,
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wantR: 3,
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},
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}
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for _, tt := range tests {
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t.Run(tt.name, func(t *testing.T) {
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gotL, gotR := skipDuplicates(tt.nums, tt.L, tt.R)
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if gotL != tt.wantL || gotR != tt.wantR {
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t.Errorf("skipDuplicates(%v, %d, %d) = (%d, %d), want (%d, %d)",
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tt.nums, tt.L, tt.R, gotL, gotR, tt.wantL, tt.wantR)
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}
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})
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}
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}

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